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Forum Index : Other Stuff : Long Alternator
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| dimpils666 Newbie  Joined: 13/06/2009 Location: CanadaPosts: 5 |
Hello fellow geeks, Jk.... I was wondering if its possible to build a long skinny alternator... 4" OD and about 61" length.. If anyone has any suggestions on what I can use for magnets, strong magnets, week magnets... Needs to produce alot of power while rotating at around 1000 rpm... Thanks Thru my eyes only can you really see the world |
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Tinker Guru  Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
I'm sure I'm not the only person reading your message and wondering just why sooo long? 
61" is almost 2 meters long and with only 100mm diameter it may be a bearing nightmare to construct and assemble. The only long skinny motors I can think about are submersible bore pumps, perhaps you could get hold of an old one and see how their internals are arranged. Good luck. Klaus |
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| dimpils666 Newbie Joined: 13/06/2009 Location: CanadaPosts: 5 |
hello tinker, I would like to know what I could use as a 'OD'(outside) diameter if its "61" long... I don't really want to say what I would be using it for until its made ...Sorry.. I'm just not sure how to go about it.. If I build a alternator say 61" long and just say thicker then 4" ID could it make more power then a normal size car alternator if I were to increase the voltage regulator as well.. I need info and were to get the parts (internals) to build something that big of size.. I can make it, i need to know were to look and what dimensions I can use so I can first draft it out with Inventor and see how everything goes together with no hitches before I build it.. If you have any Ideas you can help me out with that would be awesome. Sorry for not explaining what i intend on using it for, but just dont want to post it yet.. Thank you sorry for being a bytch with my idea. Thru my eyes only can you really see the world |
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GWatPE Senior Member  Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
A car alternator, operates at up to approx 10000 rpm, and can produce up to 50A or more for short durations. You are looking at 1000 rpm in your comparison. You appear to be looking at quite small power levels, only 50W or so. The design U seem to need could probably only need a small PM alternator component at one end. The rest would be empty space. small dia motors usually have to spin at very high speed to produce much power. Take a universal motor in a drill. Motor RPM probably in excess of 30000, for a 35mm dia armature at approx 1hp. Gordon. become more energy aware |
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herbnz Senior Member Joined: 18/02/2007 Location: New ZealandPosts: 258 |
Hi Here in NZ we have the Older FP called Gentle Annie these have design more like a conventional motor I use when high efficency is required on Hydro's. They can be joined end to end both stators and rotors with intermediate bearings I have only ever done two but nothing to stop more. Then you will have a number of windings that can be serised paralleled etc also I have rewound to suit. All comes back to whats available in Canada. Herb |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
12v DC motors end to end might work. Some automotive fan motors have a shaft out both ends, so these could be coupled in series to increase the output voltage/current. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| dimpils666 Newbie Joined: 13/06/2009 Location: CanadaPosts: 5 |
... Is it possible for me to make a 61" stator and use like just say 10 rotors back to back but yet all connected to one another running thru a pipe, machined to fit.. I can machine and weld at my fathers shop, but just knowing this info before time would help out with me not wasting mine. I have a good idea for bearings to use thats not a issue.. I wasn't giving a total speed limit with 1000rpm, that was just saying.. The actually true rpm range is not much different but it should be around 1500-2000 rpm...But anyone could simple use a gearbox to change the speed of that.. where can i pick up the wire (stator coil) from... In canada LOL.. Thru my eyes only can you really see the world |
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MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
"Needs to produce alot of power while rotating at around 1000 rpm... " If you are holding your rpm to 1000, you'll need to increase the speed at which the magnetic field is alternating (building and collapsing). At a diameter of 3", this isn't going to happen to any great extent. As stated by GWatPE an automobile's alternator is driven from a very small pulley at an engine rpm increase of about 10 to one. The diameter of the field here is about 5 or 6 inches and at average engine speeds, that puts the speed of the alternator shaft at around 10,000 rpm! This is where 40 to 50-amp surges are possible. "if I were to increase the voltage regulator as well.. " Varying the voltage regulator won't do anything if you don't first have the power necessary to regulate. If you MUST hold to a 3" diameter, a permanent-magnet brush motor spun from an external source is your best bet. Look for a motor that is very hard to turn when the input leads are shorted. If this contraption is to be powered by a windmill, the only thing I can come up with would be a mechanism that winds up a strong spring, then lets it go when the spring tension is great enough. This could be accomplished using a latching mechanism. The spring unwinding may be a way to increase your shaft rpm, but this would be intermittent short bursts of speed and would not work constantly. Hope that helps and by the way, "I'm glad you're building this thing and not me!" Sounds like a nightmare. Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| dimpils666 Newbie Joined: 13/06/2009 Location: CanadaPosts: 5 |
If i were to take an axel from a car or build mine own and turn the internals of the axel into a long ass alternator, could it be possible.. As we know driving a 100kms/hr or 65616.7979" per min only rotates a tire of 21" 1562.30rpm.. I would need to increase this as the alternator would only traveling at the speed of the actually car's momentum. I was debating on weither to use an axel connected to the main rear axel turning from a gearbox attached to the two. I know a rubber that my friend has created from a compound using certain curing agents that makes the rubber super hard but very light. Reduce weight and its able to stay cool from ceramic power added to the rubber compound to expell heat rapidly. Well its like a rubber/Urethane type compound. Could this alternator be made powerful enough to recharge another battery in a car as the electric motor is running of another battery. And could it be charged before the other battery drains. I would like to have something where the car cycles thru the batteries as it is moving.. I know there is a energy loss somewhere along the line. Thru my eyes only can you really see the world |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Okay, first off; I don't do cars. I do windmills, solar, steam and air engines--all stationary power. As for this statement: "Could this alternator be made powerful enough to recharge another battery in a car as the electric motor is running of (off?) another battery" -- this goes against one of the laws of Thermodynamics. In short, no; you can't get something from nothing (unless you're God maybe). I think it's maybe time you let the cat out of the bag. What are you trying to build? Each of your posts changes the subject slightly. If you want real help, narrow the playing field and stick to one topic at a time. That's my 2-cents' worth (IMO). If you're worried about someone copying your idea, worry about China; that's their gig. The folks here are harmless and do this for fun as well as for a chance to help others and be helped themselves. Now, if you're building a flying saucer . . . Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| dimpils666 Newbie Joined: 13/06/2009 Location: CanadaPosts: 5 |
LMAO... With my last post reply i pretty much said what the purpose of the alternator was for.. I want to use a axel attack to another axel for an electric car. I wrote in the reply ( the car's momentum) ... With a charged battery running an electrical motor can a huge alternator being charged from the car's actual driving momentum be enough to charge another battery if the alternator was connected thru a gearbox spinning from the tire Thru my eyes only can you really see the world |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
In a word; no. This is on the order of a sailboat powered by a battery-operated fan, dragging a propeller-driven generator through the water to charge the battery up again. Won't work. Sorry. Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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